malby



Feb. 3, 193 1. 5, MALBY 1,791,035

METHOD OF MAKING PLUGS Filed Sept. 11, 1929 INVENTOR ATTO'RN EY on a centerless grinder.

satisfactory to a certain degree.

I have found that I can produce plugs more economically and form them much more uni- Patented Feb. 3, 1931 I UNITED STATES" SETH G. MALBY, or .TENAFLY, new Jnitsny,- Assreivon ro Ama smw rim CHINE rnonuc'rs COMPANY, or nnonwarnn vnw JEnsnY; n ,GORPOBA'IIONIOE NEW JERSEY METHOD or mexmertues Application filed September 1i, 1929. ser al o."391f,772.

This invention relates to a method of making plugs and more particularly to a method of producing plugs having shanks, the diameters oi which are Within close tolerances.

he plugs formed by the method herein described are known in the art as piston-pin plugs. They are inserted in the ends of wrist pins to take up wear which formerly causeda great deal of trouble and incon- Prior to this invention these plugs were made by turning the plug from a rod of any suitable metal, such as. aluminum alloy, on-

an automatic turning machine, the diameter of theshank being slightly oversize. The plug and especially the shank portion thereof was then ground to the desired diameter This formly andof superior finish than those produced as above described by turning in an 7 automatic screw machine orlatne a bar or.

rod 01": any suitable metal, such as aluminum alloy, and thereby forming the desired headed plug, the shank of which is slightly undersize in diameter, upsetting the shank in any suitable manner wherebyits diameter is made slightly oversize, and finally sizing said shank within close tolerances.

It is therefore an object of this invention to provide an economical method of producing plugs.

Another object of this invention is to pro Other objects will appear from the follow-f ing description, appended claims and accompanying drawings in which: I g 7 Figure 1 designates a side elevation of a plug produced by the method constituting -"this invention.

method was Figure 2- is a top View lustrated in Figure 1. w

*Figure3 is a diagrammaticillustration (if th effinal step otthe process constituting this inventio v y In -carrying out the method comprising of the desired plug, the shan'kqofwhich is slightly undersize in diameter. In this oper ation a definite shoulder is formed atthe junction of the shank'endheadproviding a toolclearance to ensure-against the formation ofa fillet in the succeeding operation.

The shank of the plug is then upset, whereby itis made slightly greater in' diameterthan that desired. Finally, the shank is. sizedto within'close tolerances of theidiameter. The firsti operationlis fcarried out in an automatic screw machineor lathe' whereby w theplu'g 11,jh avin the desired head Qand the cylindrical Sl12111 *3 hav ng/an iundersize diametenisdonned. Though the head 2 is llustratedin the'drawings, as being frusto-,

conical in shape, the" invention 5 is notv restricted thereto.'*- The head may be made of any: desired-shape In this turning operation there is formed at the junction of said'shank this inventiomfthe" first step is the production" and headiatooliclearance't which also 'iensures against the. formation of a fillet in the operations hereinafter described. The shank 311sj then upset, iwhereby its-diameter is 1n-.

icre'a'sed int size'z andr preferably} slightly lar er than requiredsin the finished. product.

I have found'that, ifit isiupset in a die, on

a press .or by a-hammer, satisfactory results maybe obtained. .Thisupsetting step-imfrom thelathe.

As is apparent at this stage of the opera 'tion, the shank?) of the plug has a diameter slightly greater than required. It is therevfore necessary toreduce the diameter to sub beextremely accurate within close tolerances and uniform. Toattainthe'se features the plug, andespecially the shank thereof, is

I forced in a die cavityb of the die 6 mounted provesthe surface. It substantially removes i the machine tool irregularities and produces I V a shank more uniformthan. that obtained: t

in the well-known manner in a die block 7,

the die cavity having a diameter equal to that required in the finished product. As evident from Figure 3, the free end of the "shank is positioned at the entrance of the die cavity,

pressure being exerted on the head by means of a plunger 8'. The excess metal in the shank is compressed and slightly elongated. This sizes the shank to within close tolerances and produces a surface finish which is superior to that obtained by a straight lathe machine'and grinding operation. V

From the above it is apparent that I have provided a method ofvproduci-ng plugs which 3 is economical and produces plugs having a superior surface finish, the shanks thereof bea ing sized within close tolerances. The abovedescribed method may be applied to plugs of any type provided, of course, that the shanks thereof are of uniform cross section; Since 7 changes mthespec1fic-deta1ls abovedescribed w ll. readily suggest themselves to persons skilled in the art, I do not limit myself theretozexcept as set forth in'the appended claims.

I claim: '1. A method of making plugs'W-hich comprises turning a metallic rod to form a headed plug, said plug having its shank undersize in diameter, removing the machine irregularities on the surface of said shank, and sizing said shank. a 7

2.-A method of making'plugs which comprises for-ming a plug, the shank thereofrbeing undersize in diameter, oversizing the diameter of said shank, and finally sizing the 7 diameter of said shank to the desired size.

3'. A method of making plugs which com-- prises forming a plug, the shank thereof being I undersize indiameter, upsetting the shank whereby the diameter thereof. is madeoven size, and finally sizing the diameter to the de sired size. i

l. A method of making plugs which comprises turning a rod of metal to'form a headed plug having a is'hankundersize in diameter,

upsetting said shankwhereby its diameter is oversized, and finally die pressing said shank whereby its diameter is reducedto the desired a size withinclose tolerances. l

Intestimony whereof, I have aflixed'my signature to this specification:

. SETH e. MALBYQ 

